Run travis on node 6

Author: bbrala

.travis.yml

@@ -18,7 +18,7 @@ matrix:
 
 
 install:
-- if [ "$JQUERY" ] ; then nvm install stable && npm install && npm install jquery@$JQUERY && npm test ; fi
+- if [ "$JQUERY" ] ; then nvm install 6 && npm install && npm install jquery@$JQUERY && npm test ; fi
 - if [ "$DOCUMENTATION" ] ; then cd documentation && composer global require couscous/couscous ; fi
 
 script: if [ "$JQUERY" ] ; then npm test ; else /home/travis/.composer/vendor/bin/couscous travis-auto-deploy --php-version=5.5 ; fi